JP5402035B2 - Network configuration change detection / recovery method - Google Patents

Description

  The present invention relates to a communication system in which a plurality of terminal devices are connected by a ring-shaped bus, and data communication between the terminal devices is performed by a token passing system, and in particular, a network configuration change due to occurrence of an abnormality in the terminal device or deletion from the network The present invention relates to a detection / return method.

  This type of communication system is used in a wide variety of control systems in which a plurality of terminal devices composed of PLCs and the like are LAN-connected, such as a plant monitoring control system and an automation factory process centralized management system.

  As a communication method between terminal devices (nodes), a token passing method is generally used in which a token is circulated on a transmission path and a transmission right of the node is changed by the token. In the communication system using this token passing method, it is desired to secure a communication function between other healthy devices even when an abnormality occurs in a terminal device or when an addition or deletion occurs.

  In Patent Document 1, a parent station that monitors the node configuration is provided, and it is determined whether the token circulation change information is set in the parent station. When there is a change, the parent station creates token circulation information, which is used for all child stations. By transmitting the token to the terminal device and transmitting the token, the network connection form is appropriately changed from the master station. Each slave station recognizes the token transmission source and destination by receiving token circulation information from the master station.

  In Patent Document 2, at the time of token transmission, information on the own station is added to make a round of the token on the network, and the station receiving this token checks the status of the next station and determines the token transmission destination. When it is determined that an abnormality has occurred in the token transmission destination upon receipt of the token, the token is transmitted to the next healthy station after passing the abnormal station.

JP-A-8-79283 JP 2004-88310 A

  When the node configuration of the communication system is changed during operation, in Patent Document 1, the master station that becomes a monitoring station detects the configuration change, transmits the changed node information to each station, and the node configuration can be updated at each station. However, when the monitoring station fails or is deleted from the communication system, the node configuration cannot be updated in all stations because the monitoring station does not exist. Since the node configuration cannot be updated, the token circulation information becomes invalid and communication becomes impossible in the entire system.

  In this regard, Patent Document 2 eliminates the need for a station corresponding to a monitoring station, and each station itself individually detects an abnormality and determines a destination station. Therefore, when an abnormality occurs in a station, or when an addition or deletion occurs. The communication function can be secured between other healthy stations.

  However, in Patent Document 2, when a station in which an abnormality has occurred is changed to a healthy station or when a deleted station is restored, these state changes are automatically detected to restore the network configuration to the original state. I can't.

  It is an object of the present invention to eliminate the need for a conventional monitoring station, to automatically detect a change in network configuration due to an abnormality or deletion of a terminal device connected to the network, and to detect / return a change in network configuration that can also automatically restore the network configuration. To provide a method.

  In order to solve the above problems, the present invention has a configuration in which a token frame has a data field in which state information of each node is written in the order of slot numbers, and each node is mounted with a deleted non-installed slot or an abnormal node. The slot frame bypasses the token frame, the slot register stores the status information of the nodes for all slots, the transmission slot counter identifies the position of the slot information, and the multiplexer counts the transmission slot counter count from the source slot number. Data “0” is selected between the slot number and the own slot number, and when the count value of the transmission slot counter is equal to the own slot number, the own slot information is selected. Otherwise, the slot held in the slot register is selected. Select information and write to token frame Obtained by the characterized by the following method.

(1) In a token passing communication system in which a plurality of terminal devices (nodes) are connected by a ring-shaped bus and data communication between terminal devices is performed by circulating token frames.
The token frame has a source slot number field for designating each terminal device's own slot number and a data field in which status information of each node is written in the order of the slot number.
Each node
In the deleted non-mounted slot or the slot where the abnormal node is mounted, means for securing the ring shape of the transmission path by bypassing the token frame;
When receiving a token frame from the upstream node, a slot register for storing node status information for all slots written in the data field of the token frame;
A transmission slot counter that identifies the position of the slot information written in the data field by counting the number of slot information written in the data field of the token frame;
When the count value of the transmission slot counter is between the source slot number and the own slot number, data “0” is selected, and when the count value of the transmission slot counter is equal to the own slot number, the own slot information is selected, In other cases, a multiplexer that selects the slot information held in the slot register and writes it in the token frame;
It is provided with.

  As described above, according to the present invention, the token frame has a data field in which the state information of each node is written in the order of the slot number, and each node is mounted with a deleted non-installed slot or an abnormal node. The slot bypasses the token frame, the slot register stores node status information for all slots, the transmission slot counter identifies the position of the slot information, and the multiplexer counts the count value of the transmission slot counter from the transmission source slot number. Data “0” is selected up to the slot number. When the count value of the transmission slot counter is equal to the own slot number, the own slot information is selected. In other cases, the slot information held in the slot register is selected. Select it and write it to the token frame. Therefore, it eliminates the need for conventional monitoring station, the network configuration changes due to abnormal or deletion of a terminal device that is networked be automatically detected and there is an effect that can be automatically restored in the network configuration.

  The communication terminal is realized by providing a slot register, a multiplexer, and a transmission slot counter, and does not require a complicated communication procedure as in Patent Document 1. Furthermore, automatic restoration processing of the network configuration that cannot be realized in Patent Document 2 can also be performed.

The network block diagram which shows embodiment of this invention. The block diagram of a token frame. The block diagram of the input / output processing part of a token frame.

  FIG. 1 is a network configuration diagram showing an embodiment of the present invention. A plurality of terminal devices (nodes) 1 to 6 are connected by a ring-shaped transmission line, receive a token from the left node, and rotate in a clockwise direction to transmit to the right node. Each node is assigned a slot number and is assigned in ascending order from the left end to the right.

  Each node circulates a token frame or a data frame on the transmission path, and when detecting the token frame, transmits a token frame after the reception is completed, thereby circulating only one token on the transmission path. The node that transmits data transmits a data frame after the completion of reception of the token frame, and transmits the token frame after the transmission.

  In addition, a non-mounted slot from which a node is deleted (slot number 4 in the figure) or a slot in which an abnormal node is mounted secures the ring shape of the transmission path by bypassing the token frame. As a result, the token circulation information at each node is not particularly necessary, and the token can be circulated.

  Here, the status information of each node is stored in the data field of the token frame, and the token frame circulates each node to manage the status of each node by each node. Enables automatic detection of network configuration changes and automatic recovery of network configurations.

  FIG. 2 shows the configuration of the token frame. In FIG. 2, the number of slots is set to 1 to 6 as an example as in FIG. This token frame includes a flag for synchronization between the transmission source node and the transmission destination node before and after, a command type field that specifies whether the frame is a data frame or a token frame, and the terminal device of the transmission source has its own slot number. A transmission source slot number field for designating, a transmission destination slot number field for designating a data transmission destination (destination) slot number in the case of a data frame, and a data field in which status information of each node is written in the order of the slot number. . In the case of a data frame, transmission data is written in the data field.

  FIG. 3 shows a configuration of an input / output processing unit for a token frame provided in a node N (N = 1, 2,..., 6). The slot register R stores the state information of the nodes for all slots written in the data field of the token frame when the token frame is received from the upstream node. As shown in the figure, the status information of each slot specifies whether or not a major failure has occurred and the occurrence of a minor failure with the first two flag bits, writes arbitrary information with the next multiple bits, and writes it at the end. Write the module type.

  The multiplexer MPX switches the three pieces of information and writes them in the token frame, and makes this token frame circulate to the downstream node. This switching of information is either data “0”, own slot information, or slot information stored in the slot register R. The transmission slot counter C specifies the position of the slot information written in the data field by counting the number of slot information written in the data field of the token frame, and when the multiplexer MPX writes its own slot information in the token frame. Switch.

  Data switching by the multiplexer MPX will be described. First, data “0” is selected from the transmission slot number (upstream node slot number) of the received token frame to the local slot number in the count value of the transmission slot counter C, and the upstream node of the local node is selected. If there is an empty slot, all the status information is set to “0”. For example, when the node (N−1) immediately above the node N is an empty slot, the transmission source slot number of the token frame is (N−2), and the count value of the transmission slot counter C is (N− In the case of 1), data “0” is written in the field of the slot number (N−1) of the data field. Next, when the count value of the transmission slot counter C is equal to the own slot number, “own slot information” is selected. In cases other than these two, the held slot information (the contents of the slot register R) is selected.

  As a result, the slot information written in the data field of the token frame has all bits “0” for the empty slot (unmounted slot) information, and the mounted slot has an arbitrary pattern other than “0”. Even if the node configuration changes during operation with this mechanism, for example, an abnormal node or a deleted node is detected as an empty node, and the status information can be updated in all nodes by making one round of the token. In addition, when a node in which an error has occurred or a node that has been deleted returns, the status information of the node is switched from data “0” to its own slot information by turning the token once, and the network configuration can be automatically recovered.

  Therefore, in this embodiment, token circulation information and status information of each node can be managed without the need for a monitoring station, and network configuration changes due to abnormalities or deletion of terminal devices connected to the network can be automatically performed. It can be detected and the network configuration can be automatically restored.

1 to 6 nodes R slot register MPX multiplexer C transmission slot counter

Claims (1)

In a token passing communication system in which a plurality of terminal devices (nodes) are connected by a ring-shaped bus, and data communication between terminal devices is performed by circulating token frames.
The token frame has a source slot number field for designating each terminal device's own slot number and a data field in which status information of each node is written in the order of the slot number.
Each node
In the deleted non-mounted slot or the slot where the abnormal node is mounted, means for securing the ring shape of the transmission path by bypassing the token frame;
When receiving a token frame from the upstream node, a slot register for storing node status information for all slots written in the data field of the token frame;
A transmission slot counter that identifies the position of the slot information written in the data field by counting the number of slot information written in the data field of the token frame;
When the count value of the transmission slot counter is between the source slot number and the own slot number, data “0” is selected, and when the count value of the transmission slot counter is equal to the own slot number, the own slot information is selected, In other cases, a multiplexer that selects the slot information held in the slot register and writes it in the token frame;
A network configuration change detection / recovery method characterized by comprising:

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